148 VENOMOUS SNAKES AND THE PHENOMENA OF THEIR VENOMS 



reduced to one-tenth of the original; no hsemorrhagin was present. Ishizaka 

 thought that this was due to the removal of hsemorrhagin and that its 

 remaining toxicity was due to the presence of the neurotoxin. This fact is 

 interesting because of the new way of preparing haemorrhagin-free neurotoxin 

 from the Viperidas venom. Trypsin destroys the neurotoxin, as well as all 

 other active components of this venom. 



For some time controversies existed over the cause of death produced 

 rapidly by the injection of daboia venom into the circulation. Brunton, 

 Fayrer, and Cunningham considered it to be due to the direct action upon 

 the medulla. The symptoms in such a case are restlessness and difficulty in 

 preserving equihbrium, gasping, and labored respiration, followed by violent 

 convulsions and sudden exitus. Lamb and Hanna * however, demonstrated 

 that these symptoms are produced by the formation of extensive intravascular 

 thrombosis. A direct application of the venom solution to the medulla or 

 the injection of such into the spinal canal of monkey did not produce imme- 

 diate symptoms. A few hours afterward the animal appeared dull, lethargic, 

 and inclined to lie down. These are symptoms which are usually observed 

 in chronic cases when the poison is injected subcutaneously. These symp- 

 toms, however, soon passed off and the next day the monkey was all right 

 and no further symptoms developed. The above experiment appears suffi- 

 cient to exclude the primary neurotoxic nature of this venom in the case of 

 rapid death. In the chronic poisoning local and general symptoms develop, 

 but do not indicate much effect of this venom upon the nervous system, 

 mainly aff'ecting the local tissues and the blood. 



Table 6. 



Noc determined the toxicity of the venoms of different snakes before and 

 after heating them and demonstrated that the venoms which owe their toxicity 

 to the thermostabile neurotoxins suffer but trifling reduction in toxicity by 

 heating to 80° C. He separated the coagula by centrifugahzation and the 

 clear fluid was used for the test. Table 6 shows the doses of various venoms 

 necessary to kill a mouse within 1.5 to 2 hours. 



Briot and Massol state that the neurotoxins of cobra venom can easily be 

 absorbed from the mucous membrane of the rectum, and much more easily 

 than by subcutaneous injection. 



' Lamb and Hanna. Some observations on the poison of Russell's viper (Daboia russellii). Sci. Mem. 

 Off. Med. San. Dept. Gov. Ind., 1903, No. 3. 



a Ishizaka found that heating this venom to 73° C. for 15 minutes reduced its toxicity to one twenty- 

 seventh of the original strength. 



